Crystal structures, vibrational spectra and normal coordinate analysis of (Ph3PNPPh3)[OsF5Cl]•CH2Cl2 and cis-(Ph3PNPPh3)[OsF4Cl2]•CH2Cl2

By careful oxidation of the pure fluorochloroosmates(IV) with BrF3 in dichloromethane the mixed pentavalent complex anions [OsF5Cl](-) and cis-[OsF4Cl2](-) are formed. X-ray structure determinations on single crystals have been performed of (Ph3PNPPh3)[OsF5Cl]. CH2Cl2 (I) (triclinic, space group P (1) over bar, a = 12.153(5), b = 12.387(5), c = 14.229(5) Angstrom, alpha = 70.07(1), beta = 65.46(1), gamma = 72.87(1)degrees, Z = 2) and cis-(Ph3PNPPh3)[OsF4Cl2]. CH2Cl2 (2) (triclinic, space group P (1) over bar, a = 11.987(2) b = 13.083(2), c = 14.456(2) Angstrom, alpha = 66.30(1), beta = 65.47(1), gamma = 71.22(1)degrees, Z = 2). Based on the molecular parameters of the X-ray determinations the IR and Raman spectra for the anions of 1 and 2 have been assigned by normal coordinate analysis. Due to the mutual trans influences the valence force constants of asymmetrically coordinated octahedral axes F-.-Os-Cl' differ from those of the symmetric F-Os-F axes. The data are for 1: f(d)(OsF.) = 3.95, f(d)(OsF) = 4.07, f(d)(OsCl') = 2.51 and for 2: fd(OsF.) = 3.45, f(d)(OsF) = 3.97, f(d)(OsCl') = 2.42 mdyn/Angstrom.